Cutting device for sewing machines



July 6, 1937. EBERT 2,086,407

CUTTING DEVICE FOR SEWING MACHINES I Filed Jan. 23, 1935 2 Sheets-Sheet 1 July 6,1937. F. EBERT ,4

CUTTING DEVICE FOR SEWING MACHINES iied Jan. 25, 1955 2 Sheets-Sheet 2 In V6/7 o/n' ZZ /ti.

- in Fig.4, and

Patented July 6. 3

comma nEvrcE Ebert, Oberndorf-on-the-Neckar,

roe snwmc. MACHINES Ger- many, assignor to Mauser-Werke A. G., Oberndorf-on-the-Neckar, Germany, a joint-stock companyof Germany Application January 2a, 1935, Serial No. 3.170

- In Germany January'29, 1934,

. The present invention relates to cutting or trimming devices for sewingmachines havingan overhanging arm.

l'he new cutting or trimming device has the 5 great feature, that relatively small curves may be sewn on the sewing machine.

is obtained by. the-fact, that the resiliently mounted movable upperknife operates in direct This advantage neighborhood of the needle. By resiliently ar- 10 ranging the movable upper knife still furtherad.- vantages are gained. Thus, the upper knife always bears against the,s tationary1lower knifewith a certain pressure which may be adjusted according to the material to be handled. In this 10 manner, perfect'cutting or trimming is always 7 warranted the adjustment of the cutting device to diilerent widths of cutting or trimming is very much simplified. For this purpose, the lower knife may be adjusted by means 20 of a screw easily accessible fromthe front por-' tion of the head of the sewing machine; The

upper knife then automatically bears against the lower knife again.

In the accompanying drawings, forming part 25 of the specification, one embodiment accordingto the invention is shown by way of example.

In these drawings:

Fig. 1 is a side elevation of the cutting mecha- -nism embodying the present invention, partly in 30 section, J

. Fig. 2 shows a plan view of this mechanism,

fig. 3 is a side elevation, partly in section, of the mechanism, looking from the left and showing the end-cap in'position, Y

Fig. 4 is a side elevationof the upper knife, its operating link and a stripper mechanism,

Fig. 5 shows a front'elevation-of the parts illustrated in Fig. 4,

Fig.6isaplanview ofthe Figf'l is a detail sectional view taken 'on the line 1-1. of Fig. 4.

The cutting or trimming device, according to the invention forms'a self-contained unit which conveniently may beiixed to and removed from a support I in front of the-working arm of a sewing machine. A's'usual, the -trimming-device\ consists of a movable upper knife 2 and a star tibnary lower knife 3. In the'support I, a shaft I is journalled upon whichthe'hub of a link i is mounted. The free end of-the link i mimics the movable upper knife 2 and is, by means of mechanism shown a pivot I; connected to a link i the other end of which is pivotally connected to an arm 9. By

-meansofs crewsll andlLthe-armiisflxedto to the desired width of cutting or trimming.

A stripper mechanism 46 is, as shown in Figtin'g or trimming device, covered byr,-the'yieldable fold guide portion 5|.

the swinging lever J2, movedby the mechanism of thesewing machine, so that, by the movements of this swinging lever, the link 6 and therefore the upper knife 2, carried by the same, are moved also.

Bysmean's of the spring l3, surrounding the shaft Mthe upper knife 2 is permanently pressed against the stationary lower knife 3. One end of the spring l3 bears against the hub 5 of the link 6, while the other end of 'thisspring bears 10 against a sleeve which is mounted on the shaft (in a manner to be adjusted longitudinally thereof, whereupon it may be fixed in the ad.

justed position by any suitable means (not illus-; trated upon the" drawings). According to the thickness of the material to be handled, the tension of the spring l3 ma; be alteredv by adjusting the sleeve II in the longitudinal direction of the shaft 4;

For the purpose of hiring the link .6, the latter carries, as shown in Figures 4-7, a. jaw l6 in'which a pivot I! for a secand jaw I 8 is provided. The jaw l8 may be firm-v ly pressed against the jaw It by means of a screw l9. Recesses and 2|, provided in the jaws-ll and I8 respectively, form, when the latter are pressed against each other-by the screw IS, a

dove-tail recess, adapted toreceive the correspondinglmshaped lower portion 22 of the upper knife '2 which is thereby flxed to itsoperating The lower knife 3, remaining stationary during operation of the cutting or trimming device, is also arranged in a dove-tail guide of thesupport I. As shown in Fig. 2, the lower knife 3 has a slot 23 through which a screw 25 extends, serving to fix the lower knife as-well as the. throat-plate 24. The lower knife '3 me}, on loosening of the screw 25, be adjusted according ures 5 and 6, connected to the link 6, by means of a screw 41. Consequently, the stripper device 16 is compelled to perform the same movements as the upper knife 2, so that, with regard to the upper knife 2, it always assumes the most suitable position for stripping off.

As may be seen from Fig. 3, the projecting edge 48 of the stripper mechanism 46 is swingably'arran ed in a slot 49 of the throat-plate 24, so as 50 to completely cover the free space between the lower surface of the throat-plate 24 and the cut- On top,,the slot 49 is A depression SI of the end-cap corresponds in the upper knife 2 to 20 shape, as may also be seen from Fig. 3, to the shape ofthe swing'able stripper device 46, whereby a perfect stripping off is always obtained and a dropping of trimmed off fabric portions into the gripper mechanism is prevented, thus obviating any'troubles or disturbances.

What I claim is:

1. A trimming mechanism for sewing machines comprising in combination a support, a fixed lower knife mounted in said support, an upper knife adapted to be moved downwardly against saiii lower knife, an intermediate means comprising a shaft joumalled in said support, a first link, a jaw provided at the free end of said first link, said jaw having a recess formed therein, a second jaw pivoted to said first mentioned jaw and forming in combination with said first jaw a dove-tail recess adapted to receive 8. correspondingly shaped lower portion of said upper knife, said second jaw having a recess formed therein, ascrew for tightening said two jaws against each other to firmly clamp said upper knife in any adjusted operating position, a hub forming part of said first link and mo ted on said shaft, a sleeve slidably arranged on said shaft, a spring adapted to act upon said hub surroundingsaid shaft and 'bearing with its ends against said hub and said sleeve, a second link pivotally connected to said firstlink and a lever pivotally connected to said second link and connected to a member forming part of the sewing machine mechanism.

2. A trimming mechanism for sewing machines comprising in combination a support, a fixed lower knife mounted in said support, an upper knife adapted to be moved downwardly against said lower knife, said lower knife being adjustably mounted in a dove-tail recess formed in said support, a throat-plate, a screw working in a slot formed in said lower knife serving to fix said lower knife after adjustment and simultaneously holding said throat-plate in position, and intermediate means comprising a shaft journalled in said support,'a first link, a jaw provided at the free end of said first link, said jaw having a recess formed therein, a second jaw pivoted to said first mentioned jaw and forming in combination with said first jaw a dove-tail recess adapted to receive a correspondingly shaped lower por tion of said upper knife, said second jaw having a recess formed therein, a screw for tightening said two jaws against'each other to firmly clamp said upper knife in any adjusted operating position, a hub forming part of said first link and mounted on said'shaft, a sleeve slidably arranged on saidshaft, a spring adapted to act upon said I hub surrounding said shaft and bearing with its ably mounted in a dove-tailrecess formed in said ends against said hub andasaid sleeve, a second link pivotally connected to said first link, and 9.

- lever pivotally connected to said second linkand part of the' connected to a member forming sewing machine mechanism. 1

3. A trimming mechanism for sewing machines comprising in combination a support, va. fixed lower knife mounted in said support, an upper' knife adapted to be .moved downwardly against said lower knife, said lower knife being adjustsupport, a throatplate, a screw working in a slot formed in said lowerknife serving to fix said lower knife after adjustment and simultanefl recess formed therein, a second jaw pivoted to said first mentioned jaw and forming in combination with said first jaw-a dove-tail recess adapted to receive a correspondingly shaped lower portion of said upper knife, said second jaw having a recess formed therein, a screw for tightening said two jaws against each other to firmly clamp said upper knife in any: adjusted.

operating position, a hub forming part of said first link and mounted on said shaft, a sleeve 'slidably arranged on said shaft, 8. spring adapted toact upon said hub surrounding said shaft and bearing with its ends against said hub and said sleeve, a second link pivotally connected to said first link and a lever pivotally connected to said second link and connected to a member form- 'ing part of-the sewing machine mechanism, a

screw, and a stripper mechanism for removing trimmed off fabric po'rtions connected directly to said upper knife by said sorew.

4. A trimming mechanism for sewing machines comprising in combination a support,'a fixed lower knife mounted in said support, an upper knife adapted to be moved downwardly against said lower knife, said lower knife being adjustably mounted in a dove-tail recess formed in said support, a throat-plate, a screw working in aslot formed in .said lower knife serving to fix said lower knife after adjustment and simultaneously holding said'throat-plate in position, intermediate means comprising a shaft joumalled in said support, a first link, a jaw provided at the free end of said first link, said jaw having a recess formed therein, a second jaw pivoted to tion with said first jaw a dove-tail recess adapt ed to receive a correspondingly shaped lower portion of said upper knife, said second jaw havsaid first mentioned jaw andforming in combinaing a recess formed therein, a screw for tightening said two jawsagainst. each other to firmly .clamp said upper knife in any adjusted operat ing ,position, a hub forming part of. said first link and mounted on said shaft, a sleeve 'slidably arranged on said shaft, a spring adapted to act upon said hub surrounding said shaft and bearing with its ends against said hub and said sleeve,

a second link pivotally connected to said first' link and a lever pivotally connected to said second link and connected to a member forming part of the sewing machine mechanism, a screw, a-strippermechanism for removing trimmed off fabricportions connected directly to said upper knife by said screw and aprojecting edge of said stripper mechanism swingably arranged in a slot of said throat-plate in such a manner as to completely cover the free space between said throat-plate and said trimming mechanism, and a resilient fold guide serving to cover said slot from above.

' FRITZ EBERT. 

